The Lagrange Densities of Quantum Flavor Dynamics and of the Standard Model

Abstract

Today we regard leptons and quarks as fundamental fermions and we arrange them into three families (Table 22.1). The first experimental evidence for the top quark (t), with a mass of about 40 GeV, was reported in 1984 (Arnison 1984e) but this evidence has not been corroborated in the meantime. The leptons and quarks listed in Table 22.1 are called the different flavor species of the fermions. In addition to flavor the quarks possess the color degree of freedom. The masses of these fundamental particles are also given in the table. For possible ways of defining a mass for quarks, which is not an obvious procedure since the quarks are not observable as free particles, the reader is referred to Gasser (1982). The neutrino mass will be assumed to be zero although the upper experimental limit is, apart from the case of the electron neutrino, not particularly low.